Telephone system



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H. D. M PHERSON TELEPHONE SYSTEM File E l5 1921 16 Sheets-Sheet 9 1,506,912 H. 0. M PHERsoN TELEPHONE SYSTEM med Aug. 15. 1921 1a Sheets-Sheet 11 Sept. 2 1924.

Sept. 2. 1924.

H. D. M PHERSON F'ilecl i- 15. 1921 16 SheetsSheet 2 Sept. 2 1924. 1,506,912

H. D. M PHERSON TELEPHONE SYSTEM Filed Aug- 15. 1921 16 Sheets-Sheet 15 Funk (fiWade/pbia) //2 me for:

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H. D. MHCPHERSON TELEPHONE SYSTEM Filed 112- 15. 1921 16 Sheets-Sheet l4 Patented Sept. 2, 1924e UNITED STATES HUGH D. MACPHERSON.

PATENT OFFICE.

OF SUMMIT, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED. OF NEW YORK N. Y.. A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed August 15, 1921. Serial No. 492,228.

To all whom it may concern:

Be it known that I, HUGH D. MACPI-IER- soN, a citizen of the United States of America, residing at Summit, in the county of Union. State of New Jersey, have invented certain new and useful Improvements in Telephone Systems. of which the following is a full. clear, concise, and exact description.

This invention relates to improvements in telephone systems and has particular reference to a system wherein signals for a plurality of toll lines extending between widely separated otfices are transmitted over signalling paths common to said toll lines.

In certain systems of the above character it has been customary to provide visual signals for indicating the busy or idle con dition of toll lines before an outward operator so that the operator may select an idle line extending to a particular office when initiating a call thereto. It has also been proposed to employ a signaling path'common to a plurality of toll lines interconnecting distant oifices with means at each end of said path for transmitting thereover supervisory signals characteristic of each indi vidual line and incident to the establishment and release of a connection over said line. in such systems it has been necessary for the outward operator at an init-iatingotfice to communicate with the inward operator at a distant or incoming ofiice to verbally inform her of the number of the wanted line whereupon said inward operator proceeds to complete the connection, usually through a toll switching operator.

in other systems. means have also been provided for eliminating the necessity of the outward operator communicating the number of the wanted line to the incoming operator by employing a call indicator positioned before the incoming operator and operable. in response to the registration of a call by the outward operator and consequent actuation of signal transmittin means 'to indicate the number of the wanted line whereupon the incoming operator may then proceed to complete the connection. lVhen using the call indicator. means have been provided where-by signals individual to each line, which are employed for enpervising a connection over said line, and those For controlling the operation of the all indicator. are transmitted over the same signaling path whi h is common to a plu rality of lines.

An object of the present invention is to provide a system wherein a toll switchinv central otliee may be joined to a number of distant ofiices by a plurality of roups of toll lines, each of which is individual to said central oilice and one of the distant 0ffices, and wherein means are provided for automatically selecting an idle toll line extending to any one of the distant oliices and indicating the number of such line before the outward operator at said central ofiice.

Another object is to provide means where by signals individual to each line of any particular gronp which are, employed for supervising a connection over said line, and signalsfor controlling the operation of a call indicator before an incoming operator at the distant Oflice to which said group of lines extends, may be transmitted over sep arate signaling paths which are common to said group of lines.

Other objects will appear in the course o the t'ollowin; description when taken in connection with the accompanying drawings lligs. l to 16 of which, when arranged in accordance with Fig. 17, illustrate a preferred embodiment of the inventive idea.

General desomfptv'on of operation.

Briefly. the invention contemplates the pro vision of a plurality of groups of toll lines. each group extending between a central toll switching or outward office and a distant or incoming oll'ice. The number of lines in each group may vary in accordance with the volume of tradic between two oifices. It has been estimated that, under existing conditions and in view of probable later developinents in the use of toll lines the 11983? iest traffic between any two oilices such as New-York and Philadelphia, may be handled over approximately Q00 lines. The pres ent invention has been designed to accomplish the supervision of trafl'ic over a number of groups of toll transmission lines, any one of which groups may contain as many as 400 lines, although it is to be understood that this number may be increased or de creased in accordance with traffic require- Inents between two toll centers.

In order that the immense-she stove mentioned lines may be handled as expeditiously as possible, each originating or outgoing office has a number of outward operators positions thereat. In accordance with the present invention. these positions are divided into groups and the operator at each position in every group mar; participate in the establishment of a call between her office and any one of the distantoflices connected thereto. To this end, each operator is preferably prorided with a number of office keys each of which is individual to one of the distant otlices having toll lines terminating in the initiating o'iiic'e. The operation; of any one of these keys causes aparatus to function to automatically select anidle toll enact the group individual to the ofiice corresponding to the operated key and to indicate on an indicator, shown in Fig 16 at the operators position, the number ofthe line selected and to be used in completing a can. 7

Each outward opemt r is rovided with a number of cord circuits, suc 1 as indicated at A Fig. 2), any one'of which may be emplo "e to connect a calling suh-scribers line wit the selected toll line. At the outward operators position there is also provided a set of keys operable to register the ofiice, numerical and station designations of a wanted line in the distantlofiice, which oflice has been selected b; 'i the actuation of an officfe key. The n Inher register keys may be of any ptet'erret type andnpon actuation thereof by the outward operator certain relays in the cord register, shown in Fig. 1, corresponding to the operated keys, are energized to prepare circuits for the energization of similar relays in the line register, illustrated in Fig. 6.

After registering the number of the wanted line and receiving the number indication of an idle toll line L, the outward operator then connects the cord circuit with said idle line, whereupon certain operations take place which result in the connection of the cord and line re isters and the energization of relays in the latter in accordance with the condition ofrelays in the former. The codes for the various otilce, numerical and station designations of the called line. which consist of impulses of different polarities deter mined by the condition of the line register relays, are nowstored in the line register and await the transmisison of supervisory impulses to the dista t cfiic which light a uard lamp thereat individual" to the'toll line taken; for use to inform the incoming operator at the distant once that a can is a e an; n eases use. e supervisory impifes; ante-ii are individual to the line L, are transmitted immediately upon connection of the cord circuit A with the line L and while the line register relays ate o pei i ted.

The incoming operator, in response to the actuation of the signal for line L, operates an assignment key which results in "the transmission of a code of impulses to the outward oflice followed by a repetition of this code from the outward oflice to the inward otiice to associate the incoming operators caii indicatoflrig. 10) with the line register and a signaling path over which are transmitted all impulses for operatin the call indicators atithe distance ofiice. Light series of code impulses are now transmitted in accordance with the condition of the register relays in the line register, these series corresponding to the three oiiice, four numerical and one station designations of the wanted line. In response to these series of impulses the call indicator before the in coming operator is actuated to display, by means of lamps, the number oi the called ne,

The incoming o 7 orator now secures an as signment of a tol switching trunk, such as H, from the toll switching operator and at the same time informs her of the number wanted. The latter operator then connects the toll-switching trunk with the called subscribers line. The incoming operator connects theline L with the toll switching trunk which results in the release of the call indicator and-the transmission of the individual code'of line L to the outward ofi'ioe to light a guard lamp thereat and in response thereto the outward operator actuates the ringing key to signal the wanted subscriber. hen the call is answered a code oi" impulses is again transmitted to the outward ofiice to extinguish the guard lamp after which the outward operator no longer actuates the ringing key.

it the termination of a conversation the release of the connection is effected by the called subscriber replacing his receiver upon its switch hook, whereupon a code of impulses is transmitted to the outward office to again light the guard lamp to give the outward operator the disconnect signal. This operator then disconnects the cord circuit from the toll line L which causes the transmission oi a code of impulses to the inward oflice to simultaneously light the ,egua'rd lamps before the incoming and toll switching operators, who then restore the circuit to normal by disconnecting the, line 13 from the trunk H and said trunl from the called subscribers substation circuit, respefctirely.

' At'anv time during theconversation the call d i 'sci'iber may recall the outwardiopraTItoi-"bfif mor ine the switch hook up and. down. odes-s" e? impulses" are transmitted from the inward to the outward office and their reception at the latter office causes apparatus to function to flash the guard lamp before the outward operator. who thereupon connects her head set to the line.

If at the time of establishing a call the loll switching operator finds the wanted line busy, she inserts the plug of trunk H into a busy flash jack. This operation causes the guard lamp before the outward operator to flash and upon connecting her head set to the line she receives a distinctive tone indicating a busy condition on the line wanted. The release of the connection is then effected as previously referred to.

The operation of automatically selecting a toll line in the desired group and indicating the number of such line before the outward operator is illustrated in Figs. 12 to 16 inclusive of the drawings. In Fig. 16. three outward operators positions of a group. which usually contains twenty positions, are indicated. the toll line number indicator for the third position being shown in detail. As illustrated, these three positions are located in the third group of operators of which there may be five, although the apparatus for only three groups has been shown. A set of sequence relays, generally indicated at B (Fig. 15) and common to the third group of operators positions. is provided. and upon the operation of a pair of relays individual to any position of the group at which an ofl'ice key has been actuated, said sequence relays become effective to prevent any of the other operators at the remaining positions of the group from securing an assignment of an idle toll line until. the position of the first operator to initiate a call has been found by a position-finding switch. A second set of sequence relays, generally indicated at C and containing as many pairs of relays as there are groups of operators positions. is common to all of said groups of operators positions and is effective. when an operator in any group initiates a call to a certain distant offi e, to bar all other operators of all other groups from receiving an assignment of an idle toll line extending to said certain oflice until an operator-positionfinding switch has located the calling operators position, Operators in other groups may. however, secure an assignment of an idle line extending to a different distant office while the said calling operators position is being sought.

A plurality of links are provided for each group of toll lines extending between an outward and an incoming oflice. Only three of these links and associated apparatus have been indicated but it will be understood that this number may be varied in accordance with traflic conditions. In the illustration these links have been assumed to be assigned to the toll lines leading to Philadelphia, the

four conductors for the first and second links and their associated apparatus being shown in F igs. l4 and 13 respectively. while the four conductors for the third link. the apparatus of which is indicated by the rectangle D. are shown in Fig. 13. A rotary switch E is designed to preselect an idle one of these links so that when a call is initiated to Philadelphia by an outward operator in any group. the set of sequence relays C. common to said groups. is immediately con nected with the apparatus associated with the preselected link. iis apparatus con sists. in each instance. of a plurality of operator-positionfinding switches. those for the first link being indicated at F. F and F: and those for the second link at G. G and G The switches F and G cof the first and second links switches of the other links are individual the first group of operators: the switches 1 etc. to the second group of operators. and the switches F-. G etc. to the third group of operators. These various switches. when operated. function to find a calling operators position in the group to which each is individual. Thus. in the case assumed and illustrated, when the operator at the third position in the third group actuates the Philadelphia office key. the third pair of sequence relays, counting from the left. of the set C is operated and. in a manner later to be described in detail. auses th switch G of the second Philadelphia link which link has been preselected by the switch E. to hunt over its terminals until those individual to the thirdposition of the third group of operators" positions areencountered. whereupon switchqfl comes to rest. The'operation of switch G initiates the selection of an idle toll line by one of a plurality of switches. two of which are designated by K and K and shown in F is. 12. Each of these switches is designed to hunt over the terminals of twenty toll lines so that with 400 lines extended between an outward and inward office it will be necessary to provide twenty of these switchesfor each link. :If'the first switch K does not find an idle line. thesecond switchlx' will then be caused to hunt. If it fails to find an idle'line' the third switch (not shown) will be started, and so on until an idle line is located. The switch finding the idle line number indicator is then associated with a controlling mechanism. shown at the right of the dotted line in Fig. 12. which operates in conjunction with said switch and through wipers of'the switch G to cause the operation of the number indicator (Fig. 16) whereby certain lamps therein are lighted to indicate the number of line selected. After the outward operator has inserted the plug of a cord circuit, such as A. into the jack of the selected toll line,

the apparatus for Selecting and indicating this line is restored to normal so that the same may be employed for other selections and indications.

With this brief description of the inveir tion in mind it is believed that the invention will now be fully understood from the following detailed description of the operation.

Outward operator registers monbcr 0f called Zine in card circmt register.

A calling subscriber may be connected to the outgoing operator in any manner well known in the art. Since this operation forms no part of the present invention the apparatus for making this connection is not shown in its entirety. only a portion of the outgoing operators cord circuit A. which is employed to connect to the calling subscribcrs line, being illustrated.

Upon ascertaining the number of the called suliscribers line in Philadelphia from the calling subscriber, the outgoing operator first proceeds to setup this number on the cord circuit register illustrated in Figs. 1 and 2. It will be assumed that the ofiice designation of the wanted line is represented by the letters 'WAL and the station designation of said line by the letter M. The register relays are arranged in groups and those for the oflioe designations are indicated by the numerals 114 to 125. while relays for station designations are indicated by the numerals 126 to 129. The relays of the register representing the nuinher digits of called lines have been omitted for purposes of economy in space and description, but it will be understood that these number relays operate in the same manner as the office and station relays. lhe operator first depresses the key which corresponds to the first letter of the office designation. whereupon an operating circuit is established for register relay 116 of the first group. which circuit extends from ground. through the winding of relay 100. the righthand alternate contact of key 9, the right hand normal contact of key 6. the left-hand normal contact key 5, the lower normal contact of the transfer relay 102 individual to the first group of register relays. and the lower winding of relay 116 to grounded battery. An operating circuit is also established for relay 117 of the first group, which circuit extends from ground, through the winding of relay 100, left-hand alternate contact of key 9. the upper normal contact of relay 102, and the lower winding of relay 117 to grounded battery. Relay is also energized in either of these circuits. and in closing its contact establishes a circuit for relay 103 extending from grounded battery through the winding of said relay; the lower normal contact of relay 101, and thence to ground through the contact of relay 100.

Relay 103 energizes to close a circuit through its contact, the windings of relays 102 and '101 in series. and the contact of relay 113 to ground. Relays 101 and 102 do not encrgize in this circuit since they are short-circuited by the ground connected to contac of relay 100. and extending through the lower normal contact. of relay 101. and contact of relay 103. Relays 116 and 117. upon energization. are locked up through their upper windings and contacts to ground at the contact of relay 113. The operator now releases the key 9, whereupon relay 100 releases to remove the shortcircuit from the windings ot' relays 101 and 102. and these relays thereupon energize over the circuit extending to ground at the relay 113 to transfer the conductors extending from the various keys of the operators set to the normal contacts of the second group at transfer relays 104 and 105. The operator next depresses key 2 and again establishes a circuit for relay 100 and register relay 119 of the second group. said circuit extending from grounc. through the winding of relay 100. tire left-hand alternate contact of key 2,

the lower alternate contact of relay 101. the middle normal contact of relay 104 and the lower winding of relay 3119 to grounded battery. Relays 100 and 119 energize, and the latter relay locks through and contact to ground at the contact of relay 113. The 'energization of relay I00 now establishes a circuit for relay 106, extending from grounded battery, through the winding of said relay 106, the lower normal contact. of relay 104. the upper contact of relay 102. and the contact ofrelay 100 to ground. Re; lay 106 energizes, and through its contact closes a circuit in series, through the windings ot' relays 104 and to ground at the contact of relay 113. but, as before described in connection with relays 101 and 102, relays 104 and 105 are short-circuited as long as relay 100 remains operated. Upon the release of key 2. relay 100 releases to remove this short-circuit, and relays 104 and 105 thereupon energize. Relay 1'06 locks up in the circuit described for relays 104 and 105. The conductors leading from the keyboard are now extendedthrough the alternate contacts of transfer relays 101. 102 and 104. 105 to the normal contacts of relays 107 and I08. Upon the depression of the key 5, corresponding to the third letter of the ofiice designation. relays 100 and 124 are operated over a circuit extending from ground, through the winding of relay 100, the lefthand alternate contact of key 5, the lower alternate contacts of relays 102 and 105, the lower normal contact of relay 108 and the lower winding of relay 124 to battery. Relays 100*and 124 energize. and the latter relay locks through :its upper its upper winding lili) llU Contact to a 

